Room heater

ABSTRACT

A room heater is controlled according to a difference between a detected temperature detected by a first room-temperature detector and a predetermined set temperature. When a detected temperature detected by a second room-temperature detector falls below a first reference temperature, the operation is started on receiving an on-command from a thermostat. When the detected temperature by the second room-temperature detector has raised above a second reference temperature which is set higher than the first reference temperature, the operation is stopped on receiving an off-command from the thermostat. The room heater is controlled to raise a set temperature by a predetermined value if it does not receive the off-command by passing of a first predetermined period of time after having received the on-command or if the detected temperature detected by the first room-temperature detector has been at the set temperature or higher without receiving the off-command for a second predetermined period of time.

BACKGROUND

1. Technical Field

The present invention relates to a room heater including aroom-temperature detecting means (a detector which detects a roomtemperature) and a control means (a controller) configured to controltemperature by adjusting an amount of heat to be provided to room airaccording to a difference between a detected temperature detected by theroom-temperature detecting means and a predetermined set temperature.

2. Related Art

As this kind of room heater, JP 2009-150591A discloses a room heater inwhich a control means is coupled to a thermostat that is also coupled toother appliances. The thermostat includes a second room-temperaturedetecting means provided independent of a first room-temperaturedetecting means of the room heater. The thermostat is configured tooutput an on-command when a detected temperature detected by the secondroom-temperature detecting means becomes a predetermined first referencetemperature or below, and to output an off-command when the detectedtemperature detected by the second room-temperature detecting meansbecomes such a predetermined second reference temperature or above, orwhen the thermostat is manually operated to be switched off, the secondreference temperature being set higher than the first referencetemperature. On receiving an on-command from the thermostat, the controlmeans operates the room heater, and on receiving an off-command from thethermostat, the control means stops the room heater. The room heaterdisclosed in JP 2009-150591A is further configured to update a settemperature of temperature control when an on-command from thethermostat is received again according to a difference between adetected temperature detected by the first room-temperature detectingmeans of the room heater on receiving the off-command from thethermostat and the set temperature.

The control means of the room heater can only receive the on-command andthe off-command from the thermostat and cannot recognize the firstreference temperature and the second reference temperature set in thethermostat. Therefore, in order to prevent the temperature control frombeing carried out by the set temperature that has already been setwithout relation to a room temperature even if the temperature of theroom air has already been elevated, e.g., to the second referencetemperature when the off-command was outputted from the thermostat, theabove-described known room heater is arranged to update the settemperature.

If a user changes to raise the second reference temperature of thethermostat when the room heater is operating, the set temperature of theroom heater becomes lower than the second reference temperature.However, the above-described known room heater cannot recognize thesecond reference temperature of the thermostat, and the set temperaturecannot be changed when the room heater is operating. Consequently, theroom temperature is hard to rise to the second reference temperatureeven after a long period of time has passed after receiving theon-command from the thermostat. Therefore, there will continue a statein which the control means receives no off-command from the thermostat.Further, if the detected temperature detected by the firstroom-temperature detecting means of the room heater reaches the settemperature, the control means of the room heater controls temperatureby reducing an amount of heat to be provided to the room air. Therefore,the room temperature is hard to rise to the second reference temperatureeven after the temperature detected by the first room-temperaturedetecting means has been at the set temperature or higher for a longperiod of time. In this manner, the control means receives nooff-command from the thermostat. That is, even when a user intends towarm the room by raising the second reference temperature of thethermostat, there will continue a state in which the room temperaturewill not rise to the second reference temperature.

SUMMARY

In view of the above-described problem, an object of the presentinvention is to provide a room heater which is configured to raise theroom temperature close to a second reference temperature of thethermostat when the user changes to raise the second referencetemperature.

In order to solve the above-described problem, according to thisinvention, there is provided a room heater comprising: a firstroom-temperature detecting means; and a control means configured tocontrol temperature by adjusting an amount of heat to be provided toroom air according to a difference between a detected temperaturedetected by the first room-temperature detecting means and apredetermined set temperature. A thermostat including a secondroom-temperature detecting means provided separately from the firstroom-temperature detecting means of the room heater is coupled to thecontrol means. The thermostat is configured: to output an on-commandwhen a detected temperature detected by the second room-temperaturedetecting means becomes a predetermined first reference temperature orbelow; and to output an off-command when a detected temperature detectedby the second room-temperature detecting means becomes a predeterminedsecond reference temperature or above, the second reference temperaturebeing set higher than the first reference temperature. The control meansis configured to operate the room heater on receiving an on-command fromthe thermostat and to stop the room heater on receiving an off-commandfrom the thermostat. The control means carries out temperature-raisecontrol by raising a set temperature by a predetermined value or byincreasing the amount of heat to be provided to room air by apredetermined value when the control means does not receive theoff-command by passing of a first predetermined period of time afterhaving received the on-command from the thermostat or when the detectedtemperature detected by the first room-temperature detecting means ofthe room heater has been at the set temperature or higher withoutreceiving the off-command for a second predetermined period of time.

According to this invention, when the user changes to raise the secondreference temperature of the thermostat, and when the control means doesnot receive the off-command by passing of the first predetermined periodof time after having received the on-command from the thermostat or whenthe state in which the detected temperature detected by the firstroom-temperature detecting means of the room heater has been at the settemperature or higher without receiving an off-command at the settemperature or higher without receiving an off-command for the secondpredetermined period of time, the control means carries out thetemperature-raise control by raising the set temperature by thepredetermined value or by increasing the amount of heat to be providedto the room air by the predetermined value to enable to raise the roomtemperature. Therefore, when the user changes to raise the secondreference temperature of the thermostat, the room temperature can beraised close to the second reference temperature.

This invention is preferably configured to carry out temperature-raisecontrol again when no off-command is received by passing of a thirdpredetermined period of time after a previous temperature-raise control.According to this arrangement, the set temperature can be raisedstepwise or the amount of heat to be provided to the room air can beincreased stepwise, thereby raising the room temperature to the secondreference temperature.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a configuration of a room heater according to anembodiment of this invention; and

FIG. 2 is a flow diagram illustrating a control flow of the room heaterin FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates a room heater 1 according to an embodiment of thisinvention. The room heater 1 contains therein: a combustion casing 2having therein a burner 21; and a heat exchanger 3 in which combustiongas from a burner 21 flows. A supply passage 22 for supplying a fuel gasto the burner 21 has interposed therein: a solenoid valve 22 a foropening/closing the supply passage 22; and a proportional valve 22 b forvarying the flow rate of the fuel gas. In this arrangement, air issupplied from an inlet passage 23 on an upstream of the combustioncasing 2, and combustion gas is exhausted to an exhaust passage 32 viaan exhaust fan 31 provided on a downstream of the heat exchanger 3. Byoperating a convection fan 4 provided above the heat exchanger 3, roomair sucked from an air inlet 51 opened in a back face of the room heater1 is heated by exchanging heat with the heat exchanger 3 and is thenblown out of the room heater 1 as warm air from an air outlet 52 openedin a lower part of a front face of the room heater 1.

The room heater 1 includes: a first room-temperature detecting means 6for detecting the temperature of the room air sucked from the air inlet51; and a controller 7 which is generically called a control means tocontrol the temperature by adjusting the proportional valve 22 b toadjust an amount of heat to be provided to the room air according to adifference between the detected temperature detected by the firstroom-temperature detecting means 6 and a predetermined set temperature.The controller 7 has coupled thereto a thermostat 8. The thermostat 8has a second room-temperature detecting means 81 which is different fromthe first room-temperature detecting means 6 in the room heater 1 (thisroom-temperature detecting means 6 is also called “a firstroom-temperature detecting means” to distinguish between the secondroom-temperature detecting means 81). The thermostat 8 outputs anon-command when the detected temperature detected by the secondroom-temperature detecting means 81 becomes a predetermined firstreference temperature or lower, and outputs an off-command when thedetected temperature detected by the second room-temperature detectingmeans 81 becomes a predetermined second reference temperature or higher,or when the thermostat 8 is manually operated to be switched off. Thesecond reference temperature is set higher than the first referencetemperature. On receiving an on-command from the thermostat 8, thecontroller 7 starts the room heater 1 by opening the solenoid valve 22 aand by operating the exhaust fan 31 and the convection fan 4. Onreceiving an off-command from the thermostat 8, the controller 7 stopsthe room heater 1 by closing the solenoid valve 22 a and by stopping theoperation of the exhaust fan 31 and the convection fan 4. Further, thethermostat 8 is so arranged that the first reference temperature and thesecond reference temperature can be changed.

Suppose that, during the operation of the room heater 1, the userchanges to raise the second reference temperature in the thermostat 8 sothat the set temperature of the room heater 1 becomes lower than thesecond reference temperature. It is impossible on the side of the roomheater 1 to recognize the second reference temperature of the thermostat8. Therefore, even after a lapse of a long period of time on receivingof the on-command from the thermostat 8, the room temperature may not beraised to the second reference temperature. Consequently, there willcontinue a state in which the off-command is not received from thethermostat 8. When the temperature detected by the firstroom-temperature detecting means 6 of the room heater 1 reaches the settemperature, the controller 7 of the room heater 1 controls thetemperature by reducing the amount of heat to be provided to the roomair. It follows that, even if a state in which the temperature detectedby the first room-temperature detecting means 6 is the set temperatureor higher continues for a long period of time, the room temperature maynot be raised to the second reference temperature, and the controller 7receives no off-command from the thermostat 8. That is, even if the userintends to warm the room by raising the second reference temperature ofthe thermostat 8, there will continue the state in which the roomtemperature does not rise to the second reference temperature.

As a solution, the embodiment of this invention is so arranged that thecontroller 7 carries out the temperature-raise control by raising a settemperature by a predetermined value or by increasing the amount of heatto be provided to the room air by a predetermined value when: thecontroller 7 does not receive the off-command by passing (i.e., by thetime of completion) of a first predetermined period of time after havingreceived the on-command from the thermostat 8; or when the state inwhich the detected temperature detected by the first room-temperaturedetecting means 6 of the room heater 1 is the set temperature or abovehas continued for a second predetermined period of time withoutreceiving the off-command. Further, the controller 7 carries out thetemperature-raise control again when no off-command is received bypassing of a third predetermined period of time after having carried outthe previous temperature-raise control. The controller 7 updates a settemperature for controlling temperature on receiving the on-commandagain according to a difference between a detected temperature detectedby the first room-temperature detecting means 6 of the room heater 1when the off-command from the thermostat 8 is received and the settemperature. The control carried out by the room heater 1 willhereinafter be described referring to FIG. 2.

First, when, e.g., the user turns on a main power of the room heater 1,determination is made at STEP 1 whether or not the controller 7 hasreceived the on-command from the thermostat 8, that is, whether or notthe detected temperature detected by the second room-temperaturedetecting means 81 of the thermostat 8 has become the predeterminedfirst reference temperature or lower. Once the controller 7 has receivedthe on-command from the thermostat 8, the operation of the room heater 1is started at STEP 2. The control of the temperature by adjusting theamount of heat to be provided to the room air is then carried outaccording to the difference between the detected temperature Tr detectedby the first room-temperature detecting means 6 and the predeterminedset temperature Ts. In this manner, when the controller 7 startsoperating the room heater 1 on receiving the on-command from thethermostat 8, a timing operation with a timer A equipped in thecontroller 7 is started at STEP 3 (timer-A-start).

Then, at STEP 4, the controller 7 determines whether or not the firstpredetermined period of time (e.g., 20 minutes) has passed since thetimer-A-start and whether or not the detected temperature Tr detected bythe first room-temperature detecting means 6 of the room heater 1 is atthe set temperature Ts or higher and that state has continued for thesecond predetermined period of time (e.g., 10 minutes). Until the firstpredetermined period of time passes or until the state Tr≧Ts continuesfor the second predetermined period of time, the controller 7 determinesat STEP 5 whether or not the off-command from the thermostat 8 has beenreceived, that is, whether or not the detected temperature detected bythe second room-temperature detecting means 81 of the thermostat 8 hasbecome the predetermined second reference temperature or higher. Whenthe controller 7 receives the off-command from the thermostat 8, theroom heater 1 is stopped at STEP 6. Then, at STEP 7, the set temperatureTs, which is used for controlling temperature when the on-command isreceived again, is updated according to the difference between thedetected temperature Tr detected by the first room-temperature detectingmeans 6 of the room heater 1 when the off-command from the thermostat 8is received and the set temperature Ts, and then returns to STEP 1. Theset temperature Ts is updated, e.g., by adding to the previous settemperature Ts a half of the difference between the detected temperatureTr and the previous set temperature Ts. The updating of the settemperature Ts can alternatively be made by adding to the previous settemperature Ts the difference between the detected temperature Tr andthe previous set temperature Ts. In other words, the updating can alsobe made by updating the set temperature Ts to the detected temperatureTr detected by the first room-temperature detecting means 6 when theoff-command from the thermostat 8 is received.

On the other hand, when the controller 7 judges at STEP 4 that the firstpredetermined period of time has passed or the state Tr≧Ts has continuedfor the second predetermined period of time, the temperature-raisecontrol will be performed at STEP 8 by raising the set temperature Ts bythe predetermined value ΔT (e.g., 1° C.). According to this arrangement,the second reference temperature of the thermostat 8 is changed to beraised by the user. As a result, when the state in which the off-commandis not received until after passing of the first predetermined time orwhen the state Tr≧Ts continues for the second predetermined period oftime without receiving the off-command, there will be performed thetemperature-rise control to raise the set temperature Ts by thepredetermined value ΔT. It is therefore possible to raise the roomtemperature. Accordingly, when the user has changed to raise the secondreference temperature of the thermostat 8, the room temperature can bemade closer to the second reference temperature. Although notillustrated, the temperature rise control may be made by increasing theopening degree of the proportional valve 22 b so as to increase theamount of heat to be provided to the room air by a predetermined value,instead of raising the set temperature Ts by the predetermined value ΔT.According to this arrangement, in the same manner as described above,the room temperature can be made closer to the second referencetemperature.

Then at STEP 8, when the controller 7 carries out the temperature-raisecontrol by raising the set temperature Ts by the predetermined value ΔTor by increasing the amount of heat to be provided to the room air bythe predetermined value, a timing operation is started at STEP 9 with atimer B equipped in the controller 7 (timer-B-start). Then at STEP 10,the controller 7 determines whether the off-command from the thermostat8 is received or not, and at STEP 11, the controller 7 determineswhether or not the third predetermined period of time (e.g., 20 minutes)has passed after the timer-B-start. If the controller 7 receives theoff-command from the thermostat 8 by passing of the third predeterminedperiod of time, the process proceeds to STEP 6. If the controller 7receives no off-command from the thermostat 8 by passing of the thirdpredetermined period of time after the timer-B-start, the processreturns to STEP 8. According to this arrangement, the set temperature Tscan be raised stepwise or the amount of heat to be provided to the roomair can be increased stepwise, thereby raising the room temperature tothe second reference temperature.

The embodiment of this invention has been described with reference tothe drawings. This invention shall not, however, be limited to theabove-described embodiment. For example, in the above embodiment, thefirst room-temperature detecting means 6 is configured to detect thetemperature of the room temperature sucked from the air inlet 51. Itmay, however, be so arranged that the room-temperature detecting meansmay be disposed on an outer surface of the room heater 1 so that thetemperature outside the room heater 1 may be detected.

What is claimed is:
 1. A room heater comprising: a firstroom-temperature detecting means; and a control means configured tocontrol temperature by adjusting an amount of heat to be provided toroom air according to a difference between a detected temperaturedetected by the first room-temperature detecting means and apredetermined set temperature wherein a thermostat including a secondroom-temperature detecting means provided separately from the firstroom-temperature detecting means of the room heater is coupled to thecontrol means, the thermostat is configured: to output an on-commandwhen a detected temperature detected by the second room-temperaturedetecting means becomes a predetermined first reference temperature orbelow; and to output an off-command when a detected temperature detectedby the second room-temperature detecting means becomes a predeterminedsecond reference temperature or above, the second reference temperaturebeing set higher than the first reference temperature, the control meansbeing configured to operate the room heater on receiving an on-commandfrom the thermostat and to stop the room heater on receiving anoff-command from the thermostat, wherein the control means carries outtemperature-raise control by raising a set temperature by apredetermined value or by increasing the amount of heat to be providedto room air by a predetermined value when the control means does notreceive the off-command by passing of a first predetermined period oftime after having received the on-command from the thermostat or whenthe detected temperature detected by the first room-temperaturedetecting means of the room heater has been at the set temperature orhigher without receiving the off-command for a second predeterminedperiod of time.
 2. The room heater according to claim 1, wherein thecontrol means carries out temperature-raise control again when nooff-command is received by passing of a third predetermined period oftime after a previous temperature-raise control.